Fix HTTP/2 requests failing with duplicate Content-Length (#391)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Cargo.lock

@@ -8167,6 +8167,7 @@ dependencies = [
  "cookie",
  "flate2",
  "futures-util",
+ "http-body",
  "hyper-util",
  "log",
  "mime_guess",

crates-tauri/yaak-app/src/http_request.rs

@@ -414,7 +414,7 @@ async fn execute_transaction<R: Runtime>(
             sendable_request.body = Some(SendableBody::Bytes(bytes));
             None
         }
-        Some(SendableBody::Stream(stream)) => {
+        Some(SendableBody::Stream { data: stream, content_length }) => {
             // Wrap stream with TeeReader to capture data as it's read
             // Use unbounded channel to ensure all data is captured without blocking the HTTP request
             let (body_chunk_tx, body_chunk_rx) = tokio::sync::mpsc::unbounded_channel::<Vec<u8>>();
@@ -448,7 +448,7 @@ async fn execute_transaction<R: Runtime>(
                 None
             };
 
-            sendable_request.body = Some(SendableBody::Stream(pinned));
+            sendable_request.body = Some(SendableBody::Stream { data: pinned, content_length });
             handle
         }
         None => {

crates-tauri/yaak-app/src/lib.rs

@@ -1095,8 +1095,13 @@ async fn cmd_get_http_authentication_config<R: Runtime>(
 
     // Convert HashMap<String, JsonPrimitive> to serde_json::Value for rendering
     let values_json: serde_json::Value = serde_json::to_value(&values)?;
-    let rendered_json =
-        render_json_value(values_json, environment_chain, &cb, &RenderOptions::throw()).await?;
+    let rendered_json = render_json_value(
+        values_json,
+        environment_chain,
+        &cb,
+        &RenderOptions::return_empty(),
+    )
+    .await?;
 
     // Convert back to HashMap<String, JsonPrimitive>
     let rendered_values: HashMap<String, JsonPrimitive> = serde_json::from_value(rendered_json)?;

crates/yaak-http/Cargo.toml

@@ -12,6 +12,7 @@ bytes = "1.11.1"
 cookie = "0.18.1"
 flate2 = "1"
 futures-util = "0.3"
+http-body = "1"
 url = "2"
 zstd = "0.13"
 hyper-util = { version = "0.1.17", default-features = false, features = ["client-legacy"] }

crates/yaak-http/src/sender.rs

@@ -2,7 +2,9 @@ use crate::decompress::{ContentEncoding, streaming_decoder};
 use crate::error::{Error, Result};
 use crate::types::{SendableBody, SendableHttpRequest};
 use async_trait::async_trait;
+use bytes::Bytes;
 use futures_util::StreamExt;
+use http_body::{Body as HttpBody, Frame, SizeHint};
 use reqwest::{Client, Method, Version};
 use std::fmt::Display;
 use std::pin::Pin;
@@ -413,10 +415,16 @@ impl HttpSender for ReqwestSender {
             Some(SendableBody::Bytes(bytes)) => {
                 req_builder = req_builder.body(bytes);
             }
-            Some(SendableBody::Stream(stream)) => {
-                // Convert AsyncRead stream to reqwest Body
-                let stream = tokio_util::io::ReaderStream::new(stream);
-                let body = reqwest::Body::wrap_stream(stream);
+            Some(SendableBody::Stream { data, content_length }) => {
+                // Convert AsyncRead stream to reqwest Body. If content length is
+                // known, wrap with a SizedBody so hyper can set Content-Length
+                // automatically (for both HTTP/1.1 and HTTP/2).
+                let stream = tokio_util::io::ReaderStream::new(data);
+                let body = if let Some(len) = content_length {
+                    reqwest::Body::wrap(SizedBody::new(stream, len))
+                } else {
+                    reqwest::Body::wrap_stream(stream)
+                };
                 req_builder = req_builder.body(body);
             }
         }
@@ -520,6 +528,51 @@ impl HttpSender for ReqwestSender {
     }
 }
 
+/// A wrapper around a byte stream that reports a known content length via
+/// `size_hint()`. This lets hyper set the `Content-Length` header
+/// automatically based on the body size, without us having to add it as an
+/// explicit header — which can cause duplicate `Content-Length` headers and
+/// break HTTP/2.
+struct SizedBody<S> {
+    stream: std::sync::Mutex<S>,
+    remaining: u64,
+}
+
+impl<S> SizedBody<S> {
+    fn new(stream: S, content_length: u64) -> Self {
+        Self { stream: std::sync::Mutex::new(stream), remaining: content_length }
+    }
+}
+
+impl<S> HttpBody for SizedBody<S>
+where
+    S: futures_util::Stream<Item = std::result::Result<Bytes, std::io::Error>> + Send + Unpin + 'static,
+{
+    type Data = Bytes;
+    type Error = std::io::Error;
+
+    fn poll_frame(
+        self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<std::result::Result<Frame<Self::Data>, Self::Error>>> {
+        let this = self.get_mut();
+        let mut stream = this.stream.lock().unwrap();
+        match stream.poll_next_unpin(cx) {
+            Poll::Ready(Some(Ok(chunk))) => {
+                this.remaining = this.remaining.saturating_sub(chunk.len() as u64);
+                Poll::Ready(Some(Ok(Frame::data(chunk))))
+            }
+            Poll::Ready(Some(Err(e))) => Poll::Ready(Some(Err(e))),
+            Poll::Ready(None) => Poll::Ready(None),
+            Poll::Pending => Poll::Pending,
+        }
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        SizeHint::with_exact(self.remaining)
+    }
+}
+
 fn version_to_str(version: &Version) -> String {
     match *version {
         Version::HTTP_09 => "HTTP/0.9".to_string(),

crates/yaak-http/src/types.rs

@@ -16,7 +16,13 @@ pub(crate) const MULTIPART_BOUNDARY: &str = "------YaakFormBoundary";
 
 pub enum SendableBody {
     Bytes(Bytes),
-    Stream(Pin<Box<dyn AsyncRead + Send + 'static>>),
+    Stream {
+        data: Pin<Box<dyn AsyncRead + Send + 'static>>,
+        /// Known content length for the stream, if available. This is used by
+        /// the sender to set the body size hint so that hyper can set
+        /// Content-Length automatically for both HTTP/1.1 and HTTP/2.
+        content_length: Option<u64>,
+    },
 }
 
 enum SendableBodyWithMeta {
@@ -31,7 +37,10 @@ impl From<SendableBodyWithMeta> for SendableBody {
     fn from(value: SendableBodyWithMeta) -> Self {
         match value {
             SendableBodyWithMeta::Bytes(b) => SendableBody::Bytes(b),
-            SendableBodyWithMeta::Stream { data, .. } => SendableBody::Stream(data),
+            SendableBodyWithMeta::Stream { data, content_length } => SendableBody::Stream {
+                data,
+                content_length: content_length.map(|l| l as u64),
+            },
         }
     }
 }
@@ -186,23 +195,11 @@ async fn build_body(
         }
     }
 
-    // Check if Transfer-Encoding: chunked is already set
-    let has_chunked_encoding = headers.iter().any(|h| {
-        h.0.to_lowercase() == "transfer-encoding" && h.1.to_lowercase().contains("chunked")
-    });
-
-    // Add a Content-Length header only if chunked encoding is not being used
-    if !has_chunked_encoding {
-        let content_length = match body {
-            Some(SendableBodyWithMeta::Bytes(ref bytes)) => Some(bytes.len()),
-            Some(SendableBodyWithMeta::Stream { content_length, .. }) => content_length,
-            None => None,
-        };
-
-        if let Some(cl) = content_length {
-            headers.push(("Content-Length".to_string(), cl.to_string()));
-        }
-    }
+    // NOTE: Content-Length is NOT set as an explicit header here. Instead, the
+    // body's content length is carried via SendableBody::Stream { content_length }
+    // and used by the sender to set the body size hint. This lets hyper handle
+    // Content-Length automatically for both HTTP/1.1 and HTTP/2, avoiding the
+    // duplicate Content-Length that breaks HTTP/2 servers.
 
     Ok((body.map(|b| b.into()), headers))
 }
@@ -928,7 +925,27 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn test_no_content_length_with_chunked_encoding() -> Result<()> {
+    async fn test_no_content_length_header_added_by_build_body() -> Result<()> {
+        let mut body = BTreeMap::new();
+        body.insert("text".to_string(), json!("Hello, World!"));
+
+        let headers = vec![];
+
+        let (_, result_headers) =
+            build_body("POST", &Some("text/plain".to_string()), &body, headers).await?;
+
+        // Content-Length should NOT be set as an explicit header. Instead, the
+        // sender uses the body's size_hint to let hyper set it automatically,
+        // which works correctly for both HTTP/1.1 and HTTP/2.
+        let has_content_length =
+            result_headers.iter().any(|h| h.0.to_lowercase() == "content-length");
+        assert!(!has_content_length, "Content-Length should not be set as an explicit header");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn test_chunked_encoding_header_preserved() -> Result<()> {
         let mut body = BTreeMap::new();
         body.insert("text".to_string(), json!("Hello, World!"));
 
@@ -938,11 +955,6 @@ mod tests {
         let (_, result_headers) =
             build_body("POST", &Some("text/plain".to_string()), &body, headers).await?;
 
-        // Verify that Content-Length is NOT present when Transfer-Encoding: chunked is set
-        let has_content_length =
-            result_headers.iter().any(|h| h.0.to_lowercase() == "content-length");
-        assert!(!has_content_length, "Content-Length should not be present with chunked encoding");
-
         // Verify that the Transfer-Encoding header is still present
         let has_chunked = result_headers.iter().any(|h| {
             h.0.to_lowercase() == "transfer-encoding" && h.1.to_lowercase().contains("chunked")
@@ -951,31 +963,4 @@ mod tests {
 
         Ok(())
     }
-
-    #[tokio::test]
-    async fn test_content_length_without_chunked_encoding() -> Result<()> {
-        let mut body = BTreeMap::new();
-        body.insert("text".to_string(), json!("Hello, World!"));
-
-        // Headers without Transfer-Encoding: chunked
-        let headers = vec![];
-
-        let (_, result_headers) =
-            build_body("POST", &Some("text/plain".to_string()), &body, headers).await?;
-
-        // Verify that Content-Length IS present when Transfer-Encoding: chunked is NOT set
-        let content_length_header =
-            result_headers.iter().find(|h| h.0.to_lowercase() == "content-length");
-        assert!(
-            content_length_header.is_some(),
-            "Content-Length should be present without chunked encoding"
-        );
-        assert_eq!(
-            content_length_header.unwrap().1,
-            "13",
-            "Content-Length should match the body size"
-        );
-
-        Ok(())
-    }
 }

crates/yaak-templates/src/renderer.rs

@@ -81,6 +81,10 @@ impl RenderOptions {
     pub fn throw() -> Self {
         Self { error_behavior: RenderErrorBehavior::Throw }
     }
+
+    pub fn return_empty() -> Self {
+        Self { error_behavior: RenderErrorBehavior::ReturnEmpty }
+    }
 }
 
 impl RenderErrorBehavior {